Fix linkage.html failures on Mac.

The failure is due to when we initialize variables to 0, we re-create
the struct TType, and it contains a different unique id from the
original struct TType, thus leading to a different hashed name.

BUG=chromium:641129
TEST=webgl_conformance,webgl2_conformance

Change-Id: I267b97fa496f55ea59dacee93af8f6a90f3e66cb
Reviewed-on: https://chromium-review.googlesource.com/409602
Commit-Queue: Zhenyao Mo <zmo@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
diff --git a/src/compiler/translator/SymbolTable.cpp b/src/compiler/translator/SymbolTable.cpp
index 34ef025..188f810 100644
--- a/src/compiler/translator/SymbolTable.cpp
+++ b/src/compiler/translator/SymbolTable.cpp
@@ -126,6 +126,12 @@
     return symbol;
 }
 
+TSymbol *TSymbolTable::findGlobal(const TString &name) const
+{
+    ASSERT(table.size() > GLOBAL_LEVEL);
+    return table[GLOBAL_LEVEL]->find(name);
+}
+
 TSymbol *TSymbolTable::findBuiltIn(
     const TString &name, int shaderVersion) const
 {